A portion of this patent disclosure is material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
This invention relates in general to containers which can hold one or more items and, more particularly, to a method and apparatus for sealing and tracking such containers.
One common use for containers is the shipment of goods from location to another. One known type of container is known as an intermodal container. Goods are packed into the intermodal container, and a door of the container is closed and latched. Then, the container is transported to a destination by one or more vehicles, such as trucks, planes, trains and/or ships. At the destination, the container door is unlatched and opened, and the goods are removed.
The transportation industry has recognized that it is important to provide security for goods which are in such containers. As one aspect of this, the containers need to be tracked, in order to avoid the type of loss which results when the container is stolen or inadvertently misrouted or misplaced during shipment. In addition to tracking containers, there is a need to prevent goods from being removed from a container while it is in transit to its destination, even if the container itself is not stolen, misrouted or misplaced.
For this purpose, there are existing seal devices which are used to seal or lock the latch mechanism for the door of the container. The most common type of seal device includes a disposable bolt and reusable housing. The bolt is inserted through the latching mechanism of the container, and the reusable housing is then pressed onto an end of the bolt, which causes cooperating structure of the bolt and housing to completely prevent the end of the bolt from being withdrawn in a direction opposite to its insertion direction. In order to remove this seal device from a container, the disposable bolt must be cut with a bolt cutter. The end of the bolt which remains in the housing can then be removed from the housing, for example by continuing to move it in the insertion direction until it has passed completely through the housing.
Seal devices of this known type often have a unique serial number on the reusable housing. However, a thief with proper materials can cut the bolt in order to gain access to the container, and can then use an identical bolt with the reusable housing in order to again seal the container. Since the serial number on the housing remains the same, the seal device gives the impression that there has been no tampering, when in fact tampering did occur. While these types of existing techniques for sealing and tracking containers have been generally adequate for their intended purposes, they have not been satisfactory in all respects.
In this regard, tracking of containers and inspection of existing seal devices typically involve a significant degree of manual activity, which is relatively expensive. Further, for reasons discussed above, even careful manual inspection may not reveal the fact that a seal device has been removed and replaced. The National Cargo Security Council has estimated that, as of 1998, the annual cargo theft in the United States had reached a level of approximately $10 billion per year, which after adjustment for inflation is still approximately 5 times higher than 20 to 25 years ago. And this estimate reflects only the value of the lost goods. When the cost of incident investigations, insurance paperwork and insurance claims are also taken into account, the actual annual business impact of cargo theft has been estimated to be $30 billion to $60 billion per year.
The Council noted that 85% of all business security losses are attributed to the theft or loss of products while in transit. Moreover, it is estimated that 80% of theft is perpetrated internally. Many losses go unnoticed until final delivery, due in part to the nature of multi-modal transportation. By the time of delivery, backtracking to the exact point where the loss occurred is often difficult or impossible.
From the foregoing, it may be appreciated that a need has arisen for a method and apparatus which facilitate better sealing and/or tracking techniques. According to the present invention, a method and apparatus are provided to address this need, and involve: effecting a seal between first and second parts movable relative to each other between first and second positions, including the provision of sealing structure cooperable with the first and second parts in the first position thereof in a manner limiting movement of the parts away from the first position; sensing a magnetic flux characteristic which is a function of the sealing structure; and detecting a change in the magnetic flux characteristic which represents a disruption of the sealing structure.